LED Sidewall Surface Energy Reduction for Underfill Contamination
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Solution Overview
Problem
Existing semiconductor light-emitting device mounting processes face challenges with underfill materials contaminating the sidewall surfaces of LEDs, leading to poor adhesion of encapsulating materials and potential stress concentrations, which can cause premature device failure due to incompatibility and degradation.
Innovation Solution
A process involving the treatment of surfaces with a fluorocarbon-based material to lower surface energy, preventing underfill material from contaminating the sidewalls during mounting, and selectively treating the sub-mount to inhibit underfill material spread, ensuring clean and reliable bonding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If underfill material is applied between the mounting face and sub-mount during mounting, then mechanical integrity and bonding reliability are improved, but the underfill material contaminates the sidewall surfaces of the LED, causing poor adhesion of encapsulating materials and stress concentrations
Solution Approach 1:
The patent applies a surface treatment to the LED sidewall surfaces before the underfill material is applied during mounting. This preliminary treatment creates a low surface energy coating that prevents the underfill material from adhering to the sidewalls, thereby eliminating contamination issues while still allowing the underfill to perform its bonding function between the mounting face and sub-mount.
Solution Approach 2:
The invention selectively treats only the sidewall surfaces of the LED with a surface treatment material, leaving the mounting face and other surfaces unaffected. This localized treatment ensures that the underfill material is prevented from adhering only to the sidewalls, while maintaining proper adhesion at the bonding interfaces where needed.
2Reliability
If underfill material is applied to fill the gap between LED and substrate, then mechanical mounting reliability is improved, but the underfill material spreads to areas other than the area between the LED and substrate, causing contamination
Solution Approach 1:
The surface treatment is applied to the LED sidewalls before the underfill material is dispensed and applied to the substrate. This preliminary low surface energy coating on the sidewalls acts as a barrier that contains the underfill material within the intended gap area, preventing it from spreading or running up the sidewalls during the underfilling process.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The process effectively inhibits underfill material contamination, enhancing mechanical integrity and preventing stress concentrations, thereby improving the reliability and longevity of semiconductor light-emitting devices by ensuring clean and reliable bonding and encapsulation.
Implementation Method 1
treating at least one surface of the light-emitting device other than the mounting face to lower a surface energy of the at least one surface
Data Source
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Figure 3A~3C
AI summary
A process for preparing a semiconductor light-emitting device for mounting is disclosed. The light- emitting device has a mounting face for mounting to a sub-mount. The process involves treating at least one surface of the light-emitting device other than the mounting face to lower the surface energy of the at least one surface, such that when mounting the light-emitting device, an underfill material applied between the mounting face and the sub-mount is inhibited from contaminating the at least one surface.